document.getElementsByTagName("form")[0].onclick = function(e) {
	var obj = e.target;
	if(obj.tagName == "BUTTON") {
		var str = "btn_checked";
		var className = obj.className
		var checkBox = get_nextSibling(obj);
		//obj.className = (className == str)?"":str;
		if(className == str) {
			obj.className = "";
			checkBox.checked = false;
		} else {
			obj.className = str;
			checkBox.checked = true;
		}
	}
};

function get_nextSibling(n) {
	y = n.nextSibling;
	while(y.nodeType != 1) {
		y = y.nextSibling;
	}
	return y;
}